Biodiversity Flashcards
What is sampling?
Taking measurements of a limited number of individual organisms present in a particular area
What does the abundance of an organism tell us
The number of individuals of a species present in an area
What is random sampling
Means selecting individuals by chance
What is non random sampling
When the sample is not random
What are the three main techniques if non random sampling
Opportunistic
Stratified
Systematic
Explain opportunistic sampling
Weakest form of sampling. Uses organisms the are conveniently available.
Explain stratified sampling
Population can be divided into a number of strata based in particular characteristics. A random sample is then taken from each strata proportional to its size.
Explain systematic sampling
Areas within an overall population are identified and sampled separately. Often carried out using a line or belt transect.
What is sample bias
Selection may be biased. May be by accident or deliberate. Effects may be reduced using random sampling.
What is chance
Organisms selected may by chance not be representative of the whole population. Can never be completely removed. Can be minimised using a larger sample.
importance of biodiversity
essential in maintaining a balanced ecosystem as all species are dependant on each other
we rely on ecosystems as they supply us with food, oxygen and other materials
different levels biodiversity can be measured at
habitat biodiversity
species bidiversity
genetic biodiversity
biodiversity
variety of living organisms present in an area
habitat biodiversity
refers to the number of different habitats found within an area
greater the habitat biodiversity the higher the species biodiversity
species richness
the number of different species living in a particular area
species evenness
a comparison of the numbers of individuals of each species living in a community
genetic biodiversity
refers to the variety of genes that make up a species
point quadrat
consists of a frame containing a horizontal bar at set intervals a long pin can be pushed through to the ground and each species of plant the pin touches is recorded
frame quadrat
consists of a square frame divided into a grid of equal sections the type and number of species within each section is recorded
using frame quadrats
density
if individual plants can be seen clearly count them in a 1m by 1m quadrat and this will give you the density per square metre
using frame quadrats
frequency
used when individuals are hard to count, using small grids within the quadrat count the amount of sqaures the species is present in and find thee percentage
